Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Equipment rentals																	$ 3,455		$ 2,151		$ 1,834
Sales of rental equipment																	399		208		144
Sales of new equipment																	93		84		78
Contractor supplies sales																	87		85		95
Service and other revenues																	83		83		86
Total revenues	1,249	[1]	1,219	[1]	993	[1]	656	[1]	746	[2]	713	[2]	629	[2]	523	[2]	4,117	[1]	2,611	[2]	2,237
Depreciation and amortization expense																	897		480		449
Equipment rentals gross profit																	1,364		736		521
Capital expenditures																	1,369		810		374
Total assets	11,026								4,143								11,026		4,143
General Rentals [Member]
Segment Reporting Information [Line Items]
Equipment rentals																	3,188		1,953		1,693
Sales of rental equipment																	387		201		134
Sales of new equipment																	86		77		72
Contractor supplies sales																	80		79		89
Service and other revenues																	79		79		83
Total revenues																	3,820		2,389		2,071
Depreciation and amortization expense																	850		448		426
Equipment rentals gross profit																	1,239		643		461
Capital expenditures																	1,285		739		344
Total assets	10,545								3,776								10,545		3,776
Trench Safety, Power and HVAC [Member]
Segment Reporting Information [Line Items]
Equipment rentals																	267		198		141
Sales of rental equipment																	12		7		10
Sales of new equipment																	7		7		6
Contractor supplies sales																	7		6		6
Service and other revenues																	4		4		3
Total revenues																	297		222		166
Depreciation and amortization expense																	47		32		23
Equipment rentals gross profit																	125		93		60
Capital expenditures																	84		71		30
Total assets	$ 481								$ 367								$ 481		$ 367

[1] During the fourth quarter of 2012, we recognized $13 of charges related to the RSC merger. Additionally, during the quarter, we recognized restructuring charges of $6, primarily reflecting branch closure charges associated with the RSC merger. During the quarter, we also recognized asset impairment charges of $2 which are primarily reflected in non-rental depreciation and amortization and principally relate to write-offs of leasehold improvements and other fixed assets. During the fourth quarter of 2012, we redeemed our 10 7/8 percent Senior Notes and all of our outstanding 1 7/8 percent Convertible Senior Subordinated Notes were converted. Upon redemption/conversion, we recognized a loss of $72 in interest expense, net. The loss represents the difference between the net carrying amount and the total purchase/conversion price of these securities. During the quarter, we also recognized a benefit of $6 in cost of equipment rentals, excluding depreciation related to our provision for self-insurance reserves. Additionally, operating income for the fourth quarter 2012 includes $8 of costs, in the aggregate, primarily related to the merger, which should have been recognized in the second and third quarters of 2012. There is no impact on 2012 full year operating income.

[2] During the fourth quarter of 2011, we recognized $19 of charges associated with the RSC acquisition. Additionally, during the quarter, we closed 18 branches and recognized restructuring charges of $14. During the quarter, we also recognized asset impairment charges of $3 which are primarily reflected in non-rental depreciation and amortization and principally relate to write-offs of leasehold improvements and other fixed assets in connection with our closed restructuring program. In the quarter, we also purchased an aggregate of $32 of QUIPS for $32. In connection with this transaction, we retired $32 principal amount of our subordinated convertible debentures and recognized a loss of $1 in interest expense-subordinated convertible debentures, net, inclusive of the write-off of capitalized debt issuance costs. Interest expense, net for the fourth quarter of 2011 also includes a loss of $3 reflecting write-offs of debt issuance costs associated with the amendment of our ABL facility discussed above. During the quarter, we also recognized a benefit of $8 in cost of equipment rentals, excluding depreciation related to our provision for self-insurance reserves.